Temperature compensating valve lifter for internal combustion engine

ABSTRACT

A valve lifter for an internal combustion engine in which the effective length thereof is automatically varied by a temperature sensitive element rotating a screw means in the device to compensate for thermal longitudinal expansion and contraction of associated valve stem and push rod components and thus maintain a minimum constant axial clearance in the valve train at various engine operating temperatures.

United States Patent [72] Inventor Lloyd E. Miller. Jr. 1,820,890 8/1931 Spiller. 8330 South West 52 Ave.. Miami, Fla. 1.962.057 6/1934 Clutterbuck 33143 1.995.665 3/1935 Brackett [21] Appl. No 844,780 2.066.976 1/1937 Holmes [22] Filed July 25,1969 2.747,559 5/1956 Campbell [45] Patented June 15, 1971 FOREIGN PATENTS 601,725 8/1934 Germany [54] TEMPERATURE COMPENSATING VALVE LIFTER Primary Examiner-Al Lawrence Smith FOR INTERNAL COMBUSTION ENGINE Attorney-Lloyd J. Andres 3 Claims, 7 Drawing Figs.

[52] U.S.Cl 123/9019, 74/569, 123/9054 [51] Int. Cl .1 F011 1/22, ABSTRACT: A valve lifter for an internal combustion engine F011 1/ 14 in which the effective length thereof is automatically varied by [50] new of Search 123/90 a temperature sensitive element rotating a screw means in the 90/9 9054; 74/569 device to compensate for thermal longitudinal expansion and 56 Rf c Cit d contraction of associated valve stem and push rod com- 1 e es e ponents and thus maintain a minimum constant axial UNITED STATES PATENTS clearance in the valve train at various engine operating tem- 1,784,257 12/1930 Thomas 123/90 m s.

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PATENTED JUNISIBYI 3,584,611

INVIZNTOR. LLOYD E. MILLER -JR.

BY A

TEMPERATURE COMPENSATING VALVE LIFTER FOR INTERNAL COMBUSTION ENGINE This invention relates in general to a thermostatically compensating valve clearance adjusting device and more particularly to a screw means for automatically adjusting the clearance in a valve train within a desired range by the bidirectional rotation of a temperature sensitive element.

The principal object of the invention is to reduce valve train noise during engine warmup by allowing valves to be manually adjusted to the very minimum cold clearance that will insure positive valve seating, without the danger of the valves being held open and possibly burned because of thermal expansion.

Prior to the present invention, mechanical or solid" lifters, sometimes called tappets, require a manual adjustment screw on the lifter body or on the valve rocker arm which pennits the manual setting of the valves to the minimum clearance that will insure positive closing when hot. This unfortunately results in excessive noise when operating. at relatively lower starting temperatures, due to the hammering effect arising from the wide cold clearance gap in the valve train.

Hydraulic lifters employing a piston to rise in the valve train by engine oil pressure provide a considerable reduction in noise, but these lifters are highly susceptible to sticking and malfunction, clue to gum and varnish deposits on the adjustable parts from the head engine oil.

The above objections and disadvantages are overcome in the present invention, which not only has improved reliability from sticking, but which provides a net gain in engine horsepower and economy inasmuch as the present invention, unlike hydraulic lifters, does not employ a friction-producing piston element constantly rubbing in expanded contact between cam shaft and push rod.

These and other objects and advantages in one embodiment of the invention are described and shown in the following specification and drawing, in which:

FIG. 1 is an illustration of a typical overhead valve train in an internal combustion engine in reduced scale, including a thermostatically compensating lifter assembly.

FIG. 2 is an enlarged exploded view of all of the elements in the lifter shown in FIG. 1.

FIG. 3 is an enlarged cross-sectional elevation taken through section line 3-3, FIG. 1.

FIG. 4 is an enlarged cross-sectional view taken through section line 3-3, FIG. 1, showing the device when hot.

FIG. 5 is a cross-sectional plan view taken through section line 5-5, FIG. 4.

FIG. 6 is the same as FIG. 4 when the device is cold.

FIG. 7 is a plan view taken through section line 7-7, FIG. 6.

Referring to FIG. 1, the valve lifter assembly 1 is positioned for reciprocation by cam 3 in the block 2 of the engine. The assembly 1 is adapted to reciprocate push rod 4 and rocker arm 5 about the rocker shaft 6, which in turn reciprocates the stern of valve 7 against the restraining action of valve spring 8. The arm 5 usually includes an adjustment screw assembly 9 for setting up the initial clearance in the valve train, which may be from ten to twenty thousandths of an inch in automobile engines and greater in larger engines.

Referring to FIGS. 2 and 3, a hollow cylindrical lifter body 10 contains all of the compensating elements, to be hereinafter described. An internal sleeve 11 is dimensioned to be installed snugly in body 10 and is provided with half-inch diameter internal thread 12 in the upper end thereof in the order of 13 threads per inch, as shown in this embodiment.

The lower end of the sleeve 11 contains a slot 13. A base plug I4 is provided with a projection 15 extending therefrom for engaging the slot 13 when slidably inserted in the lower end of the sleeve 11. The base plug also contains a transverse slot 16, as shown, for receiving a transverse lower end 17 of a truncated conical or volute bimetal spring 18, of rectangular cross section, which spring terminates at the upper end in a transverse upper end I9.

An adjustable screw member 20 is adapted to be threaded into mating threads 12 in the upper end of sleeve Ill and has a spherical seat 21 for receiving the spherical lower end of push rod 4 and includes a lower coaxial projection 22 having a slot 23 for engagement by the upper end 10 of spring 18 including a coaxial oil outlet hole therethrough.

It is now apparent from FIG. 3 that the base plug 14! is prevented from rotation in sleeve 11 by the engagement of projection 15 in slot 13 of sleeve ll.

When assembled, as shown in FIG. 3, the lower ends 17 of spring 18 are engaged in slot 16 and the upper end 19 is engaged in slot 23. Thus, a temperature increase of the spring will produce a torsional displacement of its coils and upper end 19 to proportionately rotate screw member 20 and lower same in sleeve 11 to effectively shorten the lifter and thereby compensate for the increase in length of the stem of valve 7 and push rod 4, as shown in FIG. 1.

The internal parts of the lifter are retained in body 10 by spring clip 24, which is engaged in an internal circular groove 25 in the upper end portion of body 10, which will retain sleeve 11 and the internal parts shown in body 10.

In operation, and referring to FIG. 1, an adjustment of the clearance in the valve train is made by the assembly 9, which will establish a minimum initial clearance in the train to assure valve seating when the engine is cold. This may be 0.001- 0.002 inches. Then, after the engine is started and the block temperature begins to increase, the initially adjusted clearance will be maintained in the valve train through a wide range of engine temperature changes by the corresponding rotation of the transverse upper end 19 of the spring with relation to the base plug 14, thus rotating the screw member up or down within the mating threads 12 in the sleeve 11. Since the lower spherical end of the push rod is resting on the seat 21 in member 20, the clearance in all portions of the train will remain constant by the corresponding counter or clockwise rotation of the member 20, which follows the temperatureresponsive movement of bimetal spring 18 with respect to the lifter body 10. This adjustment is shown exaggerated in FIGS. 4 and 6, in which the screw member 20 in FIG. 4 is rotated a full turn, as compared with member 20 in FIG. 6.

It is to be noted that a bimetal spring wound clockwise, employed in conjunction with a screw member 20 having a righthand thread, has the effect, when heated, to shorten the length of the lifter. A bimetal spring wrapped] counterclockwise used with a lefbhand screw member also shortens the lifter when heated. For either case, the spring has a tendency to uncoil when heated if the spring is wound with its face having the greater expansive coefficient positioned toward the longitudinal axis.

In a typical construction having a one-half inch-- 1 3 thread per inch screw member, the spring will rotate the screw through approximately a angle when heated from ambient to normal engine operating temperature of a typical automobile engine. Since the pitch of the aforesaid screw is 0.077 inch, one quarter turn of the screw would shorten the length of the lifter by 0.0l9 inch, which is approximately the combined increase in length of typical automobile engine valve stems and push rods when hot. The initial clearance of 0.00 l 0.002 inches would still exist in a typical engine at operating temperature or when excessively overheated, since the lifter would continue to compensate past the normal range, thus providing additional insurance against burned valves.

It is also to be noted that the subject device will maintain a constant valve gap clearance should the ambient temperature fall below 0Fahrenheit, in which case the lifter will effectively lengthen to compensate for a reduction in length of cooperative valve train components.

As may be observed in the drawing, a lubrication system is preferably employed in order that the present lifter might serve as a direct replacement for many solid" and hydraulic lifters, wherein pressurized oil from the engines lubrication pump is forced through a hole 26 in the side of the lifter body and then through the screw member 20 and the hollow push rod used therewith to supply lubricant to the rocker arm assembly. In this embodiment, the heated oil is in contact with the bimetal spring 18 and serves to transfer engine heat thereto more rapidly than if the spring were surrounded by air and also provides precise free rotation of screw 20.

While the present invention has been shown incorporated into a lifter body as a preferred embodiment, it is to be understood that it is not limited to a lifter operated by the cam. The device could readily be modified to operate in series with other parts of the valve train, such as in the push rod, rocker l arm, rocker arm support in the valve stem.

This invention comprehends modifications which come within the teachings and spirit of the above specification.

Having described my invention, 1 claim:

1. A temperature compensating valve lifter in a valve train base means a cylindrical body for axial reciprocation by a cam having a coaxial cylindrical bore in one end thereof,

a cylindrical sleeve with internal threads in one end portion including base means secured in the opposite end thereof with the sleeve slidably positioned in said bore with said base means against the bottom thereof,

a fastener means engaged in the upper end of said body and bearing upon the threaded end of said sleeve for holding said base means against the bottom of said bore,

a conical torsion-type bimetal spring coaxially positioned in said sleeve with one end thereof secured to the said base means for axial angular rotation of the opposite end thereof corresponding to temperature within a predetermined range,

LII

a screw adjustment member threaded for free rotation in said internal threads and secured to the opposite end of said spring adapted portions engage and operate a valve in said train whereby a predetermined clearance in the said valve train is automatically maintained through a predetermined rang of temperatures by the corresponding rotation of said screw member with respect to said sleeve by the rotative movement of said bimetal spring.

2. The construction in claim 1 wherein said conical torsion spring is formed from flat substantially rectangular material and the opposite end portions thereof are formed parallel with and intersecting the axis of said spring.

said screw member and said base means each having a slot intersecting the axis thereof in facing relation for the respective engagement of each opposite said end portion of said spring.

3. The construction recited in claim 1 wherein said body having a hole of predetermined diameter trough the wall thereof and said sleeve having a peripheral channel in the outer periphery thereofwith a hole ofpredetermined diameter joining said cannel and said screw adjustment member having a coaxial hole of predetermined diameter therethrough whereby pressurized oil entering said first mentioned hole will traverse said channel and enter said hole through said sleeve and exit through said hole through said screw means for lubricating the adjustable elements of said lifter and feeding oil to said valve train. 

1. A temperature compensating valve lifter in a valve train base means a cylindrical body for axial reciprocation by a cam having a coaxial cylindrical bore in one end thereof, a cylindrical sleeve with internal threads in one end portion including base means secured in the opposite end thereof with the sleeve slidably positioned in said bore with said base means against the bottom thereof, a fastener means engaged in the upper end of said body and bearing upon the threaded end of said sleeve for holding said base means against the bottom of said bore, a conical torsion-type bimetal spring coaxially positioned in said sleeve with one end thereof secured to the said base means for axial angular rotation of the opposite end thereof corresponding to temperature within a predetermined range, a screw adjustment member threaded for free rotation in said internal threads and secured to the opposite end of said spring adapted portions engage and operate a valve in said train whereby a predetermined clearance in the said valve train is automatically maintained through a predetermined rang of temperatures by the corresponding rotation of said screw member with respect to said sleeve by the rotative movement of said bimetal spring.
 2. The construction in claim 1 wherein said conical torsion spring is formed from flat substantially rectangular material and the opposite end portions thereof are formed parallel with and intersecting the axis of said spring. said screw member and said base means each having a slot intersecting the axis thereof in facing relation for the respective engagement of each opposite said end portion of said spring.
 3. The construction recited in claim 1 wherein said body having a hole of predetermined diameter trough the wall thereof and said sleeVe having a peripheral channel in the outer periphery thereof with a hole of predetermined diameter joining said cannel and said screw adjustment member having a coaxial hole of predetermined diameter therethrough whereby pressurized oil entering said first mentioned hole will traverse said channel and enter said hole through said sleeve and exit through said hole through said screw means for lubricating the adjustable elements of said lifter and feeding oil to said valve train. 